Selecting local gateways for VoWiFi and ViWiFi

ABSTRACT

Selecting local gateways for VoWiFi and/or ViWiFi calls (voice traffic sessions) for a user equipment (UE) includes: receiving, by an evolved packet data gateway (ePDG), a request to initiate the voice traffic session from a WiFi router outside a cellular network that is communicatively coupled with the UE; based on at least an internet protocol (IP) address of the WiFi router or the UE, determining a geographical location of the UE; based on at least the geographical location of the UE, determining a tracking area code; based on at least the tracking area code, determining an IP address of a network gateway proximate to the UE, wherein the network gateway comprises a user plane function (UPF) and a session management function (SMF) or a packet data gateway (PGW) user plane function (PGW-U) and a PGW control plane function (PGW-C); and establishing the voice traffic session using the network gateway.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims priority toU.S. patent application Ser. No. 17/101,335, entitled “SELECTING LOCALGATEWAYS FOR VoWiFi AND ViWiFi,” filed on Nov. 23, 2020, the disclosureof which is incorporated herein by reference in its entirety.

BACKGROUND

Some cellular devices (user equipment, UEs) are able to place voice orvideo calls using a WiFi router (e.g., voice over WiFi, VoWiFi, or videoover WiFi, ViWiFi), such as a router owned by the cellular device userand connected to the internet using the user's internet service provider(ISP). Because the WiFi router is outside the control of the cellularcarrier, it is outside of the cellular network's zone of trust.Therefore, in order for the call to enter the cellular network, itpasses through an evolved packet data gateway (ePDG). An ePDG interfaceswith untrusted internet protocol (IP) systems, and acts as a securetermination node for IP security (IPsec) protocol tunnels establishedwith UEs. The call is routed by the ePDG to a network gateway.

At some point, a call initiated over WiFi may experience a hand-off tothe cellular network. The cellular network will handle the call using anetwork gateway proximate to (nearby) the UE. It is preferable for thegateway use the same network gateway for the VoWiFi or ViWiFi phase ofthe call as for the later cellular phase. However, this is unlikely tooccur if, when the VoWiFi or ViWiFi call is initiated, the ePDG does notknow the location of the UE, and instead assigns the VoWiFi or ViWiFicall to a network gateway randomly.

SUMMARY

The following summary is provided to illustrate examples disclosedherein, but is not meant to limit all examples to any particularconfiguration or sequence of operations.

A solution is disclosed for selecting local gateway for a voice overWiFi (VoWiFi) and/or a video over WiFi (ViWiFi) calls for a userequipment (UE). A solution includes: receiving, by a routing node, arequest to initiate the voice traffic session for the UE from a wirelessnode communicatively coupled with the UE, the wireless node outside acellular network, wherein the routing node comprises an evolved packetdata gateway (ePDG), and wherein the wireless node comprises a WiFirouter; based on at least an internet protocol (IP) address of thewireless node or the UE, determining a geographical location of the UE;based on at least the geographical location of the UE, determining atracking area code; based on at least the tracking area code,determining an IP address of a network gateway proximate to the UE,wherein the network gateway comprises a user plane function (UPF) nodeor a packet data gateway (PGW) user plane function (PGW-U) node, andwherein the network gateway further comprises a session managementfunction (SMF) node or a PGW control plane function (PGW-C) node; andestablishing the voice traffic session using the network gateway.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed examples are described below with reference to theaccompanying drawing figures listed below, wherein:

FIG. 1 illustrates an exemplary arrangement that may advantageouslyselect a local gateway for a voice over WiFi (VoWiFi) and/or a videoover WiFi (ViWiFi) call (a voice traffic session) for a user equipment(UE);

FIG. 2 illustrates a messaging sequence that may be used within thearrangement of FIG. 1 ;

FIG. 3 illustrates a flowchart of exemplary operations associated withselecting a gateway for a voice traffic session for a UE;

FIG. 4 illustrates another flowchart of exemplary operations associatedwith selecting a gateway for a voice traffic session for a UE; and

FIG. 5 illustrates a block diagram of a computing device that may beused as a component of the arrangement illustrated in FIG. 1 .

Corresponding reference characters indicate corresponding partsthroughout the drawings. References made throughout this disclosure.relating to specific examples, are provided for illustrative purposes,and are not meant to limit all implementations or to be interpreted asexcluding the existence of additional implementations that alsoincorporate the recited features.

DETAILED DESCRIPTION

A solution is disclosed for selecting local gateway for a voice overWiFi (VoWiFi) and/or a video over WiFi (ViWiFi) calls for a userequipment (UE). A solution includes: receiving, by a routing node (e.g.,an evolved packet data gateway (ePDG)), a request to initiate the voicetraffic session for the UE from a wireless node (e.g., a WiFi router)communicatively coupled with the UE, the wireless node outside acellular network; based on at least an internet protocol (IP) address ofthe wireless node or the UE, determining a geographical location of theUE; based on at least the geographical location of the UE, determining atracking area code; based on at least the tracking area code,determining an IP address of a network gateway (e.g., a user planefunction (UPF) or a packet data gateway (PGW) user plane function(PGW-U), and a session management function (SMF) node or a PGW controlplane function (PGW-C)) proximate to the wireless node; and establishingthe voice traffic session using the network gateway.

Aspects of the disclosure improve the speed and reliability of cellularnetworks by determining a geographical location of a UE based on atleast an IP address of the wireless node (e.g., a WiFi router) or theUE, determining a network gateway that is proximate to the wireless node(via a tracking area code), and establishing a voice traffic session(e.g., a VoWiFi or ViWiFi call) using that network gateway. Based on theIP address used by the UE on the WiFi network, an ePDG will be able todetermine the approximate location of the UE using a geolocation server.In some examples, the UE will use an IP address obtained by the WiFirouter, and the WiFi router will route VoWiFi or ViWiFi call trafficto/from the UE using network address translation (NAT). However, due tothe relatively short range of WiFi local area networks (LANs), the UEmay be expected to be physically nearby the WiFi router. Thus,determining the geographical location of the WiFi router is equivalentto determining the geographical location of the UE.

Before the ePDG selects a cellular network gateway, it will check ageolocation server (e.g., on the internet) to identify a tracking areacode (TAC) that corresponds with the geographical location of the UE.The ePDG uses the tracking area code to identify an IP address of anearby network gateway, which may include a user plane function (UPF)node and a session management function (SMF) node for 5G, or a packetdata gateway (PGW) user plane function (PGW-U) node and a PGW controlplane function (PGW-C) node for 4G. The IP address of the nearby networkgateway may actually include two IP addresses, one for a control planenode (SMF or PGW-C) and one for a user plane node (UPF or PGW-U). Insome examples, a domain name system (DNS) server is used to obtain theIP address of the nearby network gateway. In some examples, a networkrepository function (NRF) may be used to obtain the IP address of thenearby network gateway.

FIG. 1 illustrates an exemplary arrangement 100 that may advantageouslyselect a local gateway for a VoWiFi and/or ViWiFi call (a voice trafficsession 106) for a UE 102. Arrangement 100 includes a UE 102, which isplacing a VoWiFi or ViWiFi call to a UE 104. UE 102 is initiallycommunicatively coupled with wireless node 130 (e.g., a WiFi router)over an air interface 138. Wireless node 130 has an IP address 134,which may be shared with UE using NAT, and is outside cellular network110. In some examples, IP address 134 may have been assigned by a DNS onthe internet, rather than by cellular network 110. Therefore, wirelessnode 130 is outside a network trusted zone 110 a and reaches networkgateway 117 using an IPsec tunnel (e.g., a secure tunnel 132) to arouting node 120 (e.g., an ePDG), a request to initiate the voicetraffic session 106 for UE 102 from wireless node 130 communicativelycoupled with UE 102, wireless node 130 outside cellular network 110.

Network gateway 117 includes a session management node 116 (e.g., an SMFnode or a PGW-C node) and a user plane component 118 (e.g., a UPF nodeor a PGW-U node). Cellular network 110 actually contains a plurality ofgeographically-dispersed network gateways, comprising a plurality ofgeographically-dispersed session management nodes 116 a and a pluralityof geographically-dispersed user plane components 118 a. The challengeis for routing node 120 to select the correct network gateway (e.g.,network gateway 117, comprising session management node 116 and userplane component 118) from the plurality of network gateways in cellularnetwork 110. This way, voice traffic session 106 uses network gateway117, which may be the same network gateway used (or at least nearby),when voice traffic session 106 is handed off from wireless node 130 to aradio access network (RAN) 112 of cellular network 110. After thehand-off, UE 102 will communicate with RAN 112 using an air interface108, and reach network gateway 117 via an access node 114. In someexamples, access node 114 comprises an access and mobility managementfunction (AMF) node.

Further description of FIG. 1 will be made with additional reference toFIGS. 2 and 3 . FIG. 2 is a messaging sequence diagram 200 that shows aseries of messages may be used within arrangement 100, and is describedin conjunction with FIG. 3 . FIG. 3 illustrates a flow chart 300 ofexemplary operations associated with selecting a gateway for a voicetraffic session for a UE. The messages of messaging sequence diagram 200occur during various operations of flow chart 300. In some examples, atleast a portion of messaging sequence diagram 200 and at least a portionof flow chart 300 may each be performed using one or more computingdevices 500 of FIG. 5 . FIGS. 1-3 should be viewed together.

UE 102 establishes a communication session with wireless node 130, usinga message 202 (FIG. 2 ). Operation 302 includes receiving, by routingnode 120, a request to initiate the voice traffic session 106 for UE 102from wireless node 130, which is communicatively coupled with UE 102,and is outside cellular network 110. In some examples, voice trafficsession 106 comprises a VoWiFi or a ViWiFi call. In some examples,routing node 120 comprises an ePDG. In some examples, wireless node 130comprises a WiFi router. Operation 304 includes routing node 120determining IP address 134 of wireless node 130 or UE 102 (which may beshared, for example, using NAT). Operation 306 includes establishingsecure tunnel 132 between wireless node 130 and routing node 120. Insome examples, routing node 120 comprises an interface between networktrusted zone 110 a and a node outside network trusted zone 110 a.Wireless node 130 is outside network trust zone 110 a.

In some examples, establishing a secure tunnel between wireless node 130and routing node 120 uses an IPsec protocol. IPsec is a secure networkprotocol suite that authenticates and encrypts packets of data toprovide secure encrypted communication between two nodes over anInternet Protocol network, for example to provide data authentication,integrity, and confidentiality. Operations 302-306 are represented, inan abbreviated form, by message 204 and message 206.

Operation 308 includes, based on at least IP address 134 (the IP addressof wireless node 130 and/or UE 104) determining a geographical location122 of UE 104. This is represented by message 208 and message 210, inwhich routing node 120 queries a geolocation server 140, which has adatabase 142 relating IP addresses with geographical locations.Operation 310 includes, based on at least geographical location 122 ofUE 104, determining a tracking area code 126. A tracking area code (TAC)is a code set by cellular operators to define operating regions, andidentify locations of network resources (e.g., network gateways). Forexample, a medium-sized metropolitan area may have three or fourdifferent tracking area codes, which divide the metropolitan area into aplurality of zones. In some examples, multiple network gateways may beassigned to a single tracking area code. In some examples, routing node120 has a list 124 of tracking area codes with their geographical areasidentified, and operation 310 includes routing node 120 searching list124 to identify a specific tracking area code (e.g., tracking area code126) that covers geographical location 122.

Operation 312 includes, based on at least the tracking area code 126,determining IP address 128 of network gateway 117 proximate to wirelessnode 130. In some examples, network gateway 117 comprises a UPF node ora PGW-U node (user plane component 118). In some examples, networkgateway 117 further comprises an SMF node or a PGW-C node (sessionmanagement node 116). In some examples, determining IP address 128 ofnetwork gateway 117 comprises querying DNS server 144, which has a list146 correlating IP addresses with tracking area codes. For example,routing node 120 sends tracking area code 126 to DNS server 144, and DNSserver 144 returns at least IP address 128 of network gateway 117 torouting node 120. In some examples, determining IP address of networkgateway 117 comprises determining a first IP address of a UPF or a PGW-Uand determining a second IP address of an SMF or a PGW-C. Operation 312is represented by message 212 and message 214. Routing node 120 has thusobtained IP address 134, used IP address 134 to obtain geographicallocation 122, used geographical location 122 to obtain tracking areacode 126, and used tracking area code 126 to learn IP address 128 ofnetwork gateway 117 that is proximate UE 102.

Operation 314 includes establishing voice traffic session 106 usingnetwork gateway 117. This is indicated with messages 216-222, in whichrouting node 120 communicates with session management node 116 and userplane component 118 to set up voice traffic session 106 for UE 102. TheVoWiFi or ViWiFi phase of voice traffic session 106 is represented inFIG. 2 as messages 106 a, 106 b, 106 c, and 106 d, showingrepresentative relay points. In some examples, voice traffic session 106is relayed by a larger number of nodes than is illustrated. Operation316 represents the ongoing VoWiFi or ViWiFi phase of voice trafficsession 106.

A decision 318 determines whether a handover is to occur, or whethervoice traffic session 106 remains as VoWiFi or ViWiFi. This may betriggered, for example, by UE establishing a communication session withRAN 112, which assigns UE 104 to session management node 116 (or anothernearby session management node) to handle the cellular call traffic.This is indicated with message 224, from UE 102 to RAN 112, and message226, from RAN 112 to session management node 116. When a handover tocellular does occur (e.g., UE uses RAN 112 rather than wireless node 130for the voice or video call), operation 320 includes performing ahandover of established voice traffic session 106 from wireless node 130to RAN 112 of cellular network 110. This is indicated with messages228-238. Session management node 116 alerts routing node 120 (message228) and user plane component 118 (message 230), which both respond(messages 232 and 234) and, in some examples, routing node 120 alsocommunicates with user plane component 118 (messages 236 and 238) toalert user plane component 118 that voice traffic session 106 will nolonger be passed through routing node 120. The cellular phase of voicetraffic session 106 is represented in FIG. 2 as messages 106 a and 106f, showing representative relay points. In some examples, voice trafficsession 106 is relayed by a larger number of nodes than is illustrated.

FIG. 4 illustrates a flowchart 400 of exemplary operations associatedwith selecting a gateway for a voice traffic session for a UE. In someexamples, at least a portion of flowchart 400 may be performed using oneor more computing devices 500 of FIG. 5 . Flowchart 400 commences withoperation 402, which includes receiving, by a session management node,from an access node, a request for the voice traffic session for the UE.Operation 404 includes determining, by the session management node, arequested traffic type for the voice traffic session, wherein therequested traffic type comprises a first traffic type or a secondtraffic type (e.g., VoWiFi or ViWiFi). Operation 406 includesdetermining whether the session management node is connected to a firstuser plane function that can support the requested traffic type.Operation 408 includes, based on at least determining that the firstuser plane function can support the requested traffic type, establishingthe requested voice traffic session for the UE using the first userplane function. Operation 410 includes, based on at least determiningthat the first user plane function cannot support the requested traffictype, connecting, by the session management node, to a second user planefunction that can support the requested traffic type. Operation 412includes, based on at least connecting to the second user planefunction, establishing the requested voice traffic session for the UEusing the second user plane function.

FIG. 5 illustrates a block diagram of computing device 500 that may beused as a component of arrangement 100 of FIG. 1 , for example, as anyother component described herein that may require computational orstorage capacity. Computing device 500 has at least a processor 502 anda memory 504 that holds program code 510, data area 520, and other logicand storage 530. Memory 504 is any device allowing information, such ascomputer executable instructions and/or other data, to be stored andretrieved. For example, memory 504 may include one or more random accessmemory (RAM) modules, flash memory modules, hard disks, solid-statedisks, persistent memory devices, and/or optical disks. Program code 510comprises computer executable instructions and computer executablecomponents including any instructions necessary to perform operationsdescribed herein. Data area 520 holds any data necessary to performoperations described herein. Memory 504 also includes other logic andstorage 530 that performs or facilitates other functions disclosedherein or otherwise required of computing device 500. An input/output(I/O) component 540 facilitates receiving input from users and otherdevices and generating displays for users and outputs for other devices.A network interface 550 permits communication over a network 560 with aremote node 570, which may represent another implementation of computingdevice 500. For example, a remote node 570 may represent another of theabove-noted nodes within arrangement 100.

Additional Examples

An exemplary system for selecting a gateway for a voice traffic sessionfor UE, the system comprises: a processor; and a computer-readablemedium storing instructions that are operative upon execution by theprocessor to: receive, by a routing node, a request to initiate thevoice traffic session for the UE from a wireless node communicativelycoupled with the UE, the wireless node outside a cellular network; basedon at least an IP address of the wireless node or the UE, determine ageographical location of the UE; based on at least the geographicallocation of the UE, determine a tracking area code; based on at leastthe tracking area code, determine an IP address of a network gatewayproximate to the UE; and establish the voice traffic session using thenetwork gateway.

An exemplary method of selecting a gateway for a voice traffic sessionfor a UE comprises: receiving, by a routing node, a request to initiatethe voice traffic session for the UE from a wireless nodecommunicatively coupled with the UE, the wireless node outside acellular network; based on at least an IP address of the wireless nodeor the UE, determining a geographical location of the UE; based on atleast the geographical location of the UE, determining a tracking areacode; based on at least the tracking area code, determining an IPaddress of a network gateway proximate to the UE; and establishing thevoice traffic session using the network gateway.

One or more exemplary computer storage devices has computer-executableinstructions stored thereon for selecting a gateway for a voice trafficsession for a UE, which, on execution by a computer, cause the computerto perform operations comprising: receiving, by a routing node, arequest to initiate the voice traffic session for the UE from a wirelessnode communicatively coupled with the UE, the wireless node outside acellular network; based on at least an IP address of the wireless nodeor the UE, determining a geographical location of the UE; based on atleast the geographical location of the UE, determining a tracking areacode; based on at least the tracking area code, determining an IPaddress of a network gateway proximate to the UE; and establishing thevoice traffic session using the network gateway.

Alternatively, or in addition to the other examples described herein,examples include any combination of the following:

-   -   the voice traffic session comprises a VoWiFi or a ViWiFi call;    -   determining the IP address of the network gateway comprises        querying a DNS server;    -   the routing node comprises an interface between a network        trusted zone and a node outside the network trusted zone;    -   the wireless node is outside the network trust zone;    -   establishing a secure tunnel between the wireless node and the        routing node;    -   the routing node comprises an ePDG;    -   the wireless node comprises a WiFi router;    -   the network gateway comprises a UPF node or a PGW-U node;    -   the network gateway further comprises an SMF node or a PGW-C        node;    -   performing a handover of the established voice traffic session        from the wireless node to a RAN of the cellular network;    -   determining the IP address of the wireless node;    -   determining the IP address of the UE;    -   establishing a secure tunnel between the wireless node and the        routing node using IP security (IPsec) protocol; and    -   determining an IP address of a network gateway proximate to the        UE comprises determining a first IP address of a UPF or a PGW-U        and determining a second IP address of an SMF or a PGW-C.

The order of execution or performance of the operations in examples ofthe disclosure illustrated and described herein is not essential, unlessotherwise specified. That is, the operations may be performed in anyorder, unless otherwise specified, and examples of the disclosure mayinclude additional or fewer operations than those disclosed herein. Forexample, it is contemplated that executing or performing a particularoperation before, contemporaneously with, or after another operation iswithin the scope of aspects of the disclosure. It will be understoodthat the benefits and advantages described above may relate to oneembodiment or may relate to several embodiments. When introducingelements of aspects of the disclosure or the examples thereof, thearticles “a,” “an,” “the,” and “said” are intended to mean that thereare one or more of the elements. The terms “comprising,” “including,”and “having” are intended to be inclusive and mean that there may beadditional elements other than the listed elements. The term “exemplary”is intended to mean “an example of.”

Having described aspects of the disclosure in detail, it will beapparent that modifications and variations are possible withoutdeparting from the scope of aspects of the disclosure as defined in theappended claims. As various changes may be made in the aboveconstructions, products, and methods without departing from the scope ofaspects of the disclosure, it is intended that all matter contained inthe above description and shown in the accompanying drawings shall beinterpreted as illustrative and not in a limiting sense.

What is claimed is:
 1. A method of selecting a gateway for a voicetraffic session for a user equipment (UE), the method comprising:receiving, by a routing node, a request to initiate the voice trafficsession for the UE from a wireless node communicatively coupled with theUE, the wireless node outside a cellular network, wherein the routingnode comprises an evolved packet data gateway (ePDG), and wherein thewireless node comprises a WiFi router; based on at least an internetprotocol (IP) address of the wireless node or the UE, determining ageographical location of the UE; based on at least the geographicallocation of the UE, determining a tracking area code; based on at leastthe tracking area code, determining an IP address of a network gatewayproximate to the UE, wherein the network gateway comprises a user planefunction (UPF) node or a packet data gateway (PGW) user plane function(PGW-U) node, and wherein the network gateway further comprises asession management function (SMF) node or a PGW control plane function(PGW-C) node; and establishing the voice traffic session using thenetwork gateway.
 2. The method of claim 1, wherein the voice trafficsession comprises a voice over WiFi (VoWiFi) or a video over WiFi(ViWiFi) call.
 3. The method of claim 1, wherein determining the IPaddress of the network gateway comprises querying a domain name system(DNS) server.
 4. The method of claim 1, wherein the routing nodecomprises an interface between a network trusted zone and a node outsidethe network trusted zone, and wherein the wireless node is outside thenetwork trust zone.
 5. The method of claim 4, further comprising:establishing a secure tunnel between the wireless node and the routingnode.
 6. The method of claim 1, further comprising: performing ahandover of the established voice traffic session from the wireless nodeto a RAN of the cellular network.
 7. The method of claim 1, furthercomprising: performing a handover of the established voice trafficsession from the wireless node to a radio access network (RAN) of thecellular network.
 8. A system for selecting a gateway for a voicetraffic session for a user equipment (UE), the system comprising: aprocessor; and a computer-readable medium storing instructions that areoperative upon execution by the processor to: receive, by a routingnode, a request to initiate the voice traffic session for the UE from awireless node communicatively coupled with the UE, the wireless nodeoutside a cellular network, wherein the routing node comprises anevolved packet data gateway (ePDG), and wherein the wireless nodecomprises a WiFi router; based on at least an internet protocol (IP)address of the wireless node or the UE, determine a geographicallocation of the UE; based on at least the geographical location of theUE, determine a tracking area code; based on at least the tracking areacode, determine an IP address of a network gateway proximate to the UE,wherein the network gateway comprises a user plane function (UPF) nodeor a packet data gateway (PGW) user plane function (PGW-U) node, andwherein the network gateway further comprises a session managementfunction (SMF) node or a PGW control plane function (PGW-C) node; andestablish the voice traffic session using the network gateway.
 9. Thesystem of claim 8, wherein the voice traffic session comprises a voiceover WiFi (VoWiFi) or a video over WiFi (ViWiFi) call.
 10. The system ofclaim 8, wherein determining the IP address of the network gatewaycomprises querying a domain name system (DNS) server.
 11. The system ofclaim 8, wherein the routing node comprises an interface between anetwork trusted zone and a node outside the network trusted zone, andwherein the wireless node is outside the network trust zone.
 12. Thesystem of claim 11, wherein the operations are further operative to:establish a secure tunnel between the wireless node and the routingnode.
 13. The system of claim 8, wherein the operations are furtheroperative to: perform a handover of the established voice trafficsession from the wireless node to a RAN of the cellular network.
 14. Thesystem of claim 8, wherein the operations are further operative to:perform a handover of the established voice traffic session from thewireless node to a radio access network (RAN) of the cellular network.15. One or more computer storage devices having computer-executableinstructions stored thereon for selecting a gateway for a voice trafficsession for a user equipment (UE), which, on execution by a computer,cause the computer to perform operations comprising: receiving, by arouting node, a request to initiate the voice traffic session for the UEfrom a wireless node communicatively coupled with the UE, the wirelessnode outside a cellular network, wherein the routing node comprises anevolved packet data gateway (ePDG), and wherein the wireless nodecomprises a WiFi router; based on at least an internet protocol (IP)address of the wireless node or the UE, determining a geographicallocation of the UE; based on at least the geographical location of theUE, determining a tracking area code; based on at least the trackingarea code, determining an IP address of a network gateway proximate tothe UE, wherein the network gateway comprises a user plane function(UPF) node or a packet data gateway (PGW) user plane function (PGW-U)node, and wherein the network gateway further comprises a sessionmanagement function (SMF) node or a PGW control plane function (PGW-C)node; and establishing the voice traffic session using the networkgateway.
 16. The one or more computer storage devices of claim 15,wherein the voice traffic session comprises a voice over WiFi (VoWiFi)or a video over WiFi (ViWiFi) call.
 17. The one or more computer storagedevices of claim 15, wherein determining the IP address of the networkgateway comprises querying a domain name system (DNS) server.
 18. Theone or more computer storage devices of claim 15, wherein the routingnode comprises an interface between a network trusted zone and a nodeoutside the network trusted zone, and wherein the wireless node isoutside the network trust zone.
 19. The one or more computer storagedevices of claim 18, wherein the operations further comprise:establishing a secure tunnel between the wireless node and the routingnode.
 20. The one or more computer storage devices of claim 15, whereinthe operations further comprise: performing a handover of theestablished voice traffic session from the wireless node to a RAN of thecellular network.